X-ray Study on the Ferroelectric Phase Transition of NaNO_2

概要

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The disordered structure above the Curie temperature (about 160℃) of NaNO_2 was studied by the X-ray diffuse scattering. The observed diffuse scattering, the satellites or the diffuse maxima and the plate-like diffuse scattering normal to the b* axis around them, can be interpreted on the basis of a certain disordered arrangement of two kinds of structure units. The atomic positions in each structure unit were determined from the relative intensity of the Bragg reflections and that of the satellites. The proposed model for the arrangement is the uniform mixing along the a axis of two kinds of small plate-like domains with antiparallel polarizations, "microdomains", whose widths are of the order of several lattice constants. In the real crystal there is a certain degree of disturbance in the uniform mixing along the a axis, and each microdomain has a certain degree of disorder. The disturbance and the disorder increase with increasing temperature, but the ordered alignment along the b axis remains in some degree up to about 240℃. The microdomain structure is similar to the structure of the antiferroelectrics, since the polarization of microdomain can be reversed by the external electric field.
社団法人日本物理学会の論文
1963-08-05